Glossary

Glossary: D

deciduous

Relating to seasonal loss of leaves; relating to teeth that are replaced by others.

deciduous forest

A temperate or tropical forest with moderate rainfall and marked seasons. The trees usually shed their leaves during either cold or dry seasons.

decomposer

An animal or microbe that uses dead plants and animals as food.

demographic

Relating to the statistical study of the age and sex distribution and size of a population of animals, and the changes within these parameters.

den

A shelter, natural or constructed, used for sleeping, for giving birth and raising young, and/or for providing shelter during winter.

density dependence

The phenomenon by which the values of vital rates such as survivorship and fecundity depend on the density of the population.

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

desiccation

the process of drying up

detritivore

an animal that mainly eats decomposed plants and/or animals

detritus

particles of organic material from dead and decomposing organisms. Detritus is the result of the activity of decomposers (organisms that decompose organic material).

diadromous

Referring to fish that must migrate between fresh and salt at some point in their life cycle.

diapause

a period of time when growth or development is suspended in insects and other invertebrates, it can usually only be ended the appropriate environmental stimulus.

dicotyledon

One of the classes of flowering plants, characterized by the presence of two seed leaves in the young plant, and by net-veined, often broad leaves, in mature plants. Includes deciduous trees.

digit

A finger or toe.

digitigrade

Relating to an animal that walks on its toes; as opposed to plantigrade.

dimorphism

The occurrence of two distinct forms of structure, size, coloring, or other characteristic in a single species. Sexual dimorphism occurs where dimorphism exists between males and females.

direct development

a pattern of development from egg to adult where the intermediate forms resemble the adult, morphologicallly and ecologically. Examples are amphibians which do not go through a larval stage and many other vertebrates.

discoidal

shaped flat and round like a disc

dispersal

Movement of an animal away from its previous home range. Often refers to the movement of a young animal away from the home range where it was born.

display

Any conspicuous pattern of behavior that conveys information to others, usually to members of the same species; e.g. threat or courtship displays.

distal

Farthest from the body.

diurnal

1. active during the day, 2. lasting for one day.

diversity - alpha

The number of species coexisting within a uniform habitat or a single community (this is the traditional concept of species diversity).

diversity - beta

As habitats change along a topographic or climatic gradient, new species are encountered as other species drop out, and this species turnover rate is termed beta diversity - a function of changing habitat. An example would be the rate at which the species composition of moss communities changes as you go higher on a mountain slope.

diversity - gamma

The rate at which additional species are encountered as geographic replacements within a habitat type in different localities; i.e., the species turnover rate with distance between sites of similar habitat, or with expanding geographic areas.

dominance hierarchies

ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates

dormant

a state in which body functions become very slow, this includes conditions like hibernation, aestivation, torpor, and diapause.

dorsal

On the upper or top side or surface; e.g. dorsal fin.

drug

a substance used for the diagnosis, cure, mitigation, treatment, or prevention of disease

duets

to jointly display, usually with sounds in a highly coordinated fashion, at the same time as one other individual of the same species, often a mate